Convective / Storm Discussion - 22nd December 2013 - 2014 onwards

[Jane Louise]

How cool, we have thunderstorms in December!   Please carry on here folks ......

Edited December 22, 2013 by Jane Louise

[Jane Louise]

Just had an intense downpour of hail . The sky was almost black. No thunder and lightning though.

[Cloud 10]

Some nice looking convective clouds around these parts at the moment,this

one taken an hour ago.

 

 

 

Another shower passing through at the moment which is falling as snow.

[Barbmac]

Just had a short, sharp and heavy hail shower pass through here, street is white.

[MP-R]

Stormy weather arriving here now - very blowy with a mix of hail and sleet falling. Going very dark!

[A.J]

as reported in the S West regional thread, thunderstorm currently here in Lyneham...Loud thunder and plenty of hail falling

 

First thunder heard since July!

Edited December 22, 2013 by ajpoolshark

[Jane Louise]

Just been across the fields and the cloudscapes are great. Three beautiful anvils in every direction and one produced a moderate icy downpour of rain.

[ZONE 51]

Radar indicates a weak storm developed and passed not too far south of Derby recently, having now just passed Nottingham.  Interesting given that region of convective activity reinvigorated well inland, away from reliable moisture source. Cold air aloft currently residing over N Midlands and northward, though, which has created steep lapse rates in the mid levels and generated marginal CAPE, allowing for sporadic lightning. 

 

gfs_lapse2_eur6.png

 

CAPE again likely pool over relatively mild waters between Tuesday and Thursday as deep trough and associated advection of cold air at 500mb overspreads the country, so small chance of Christmas time thunderstorms for those near to southern and western coasts. 

Last year Christmas morning had one spectacular TSM during dark hours, quite unusual for time of year.

Edited December 23, 2013 by ElectricSnowStorm

[Cloud 10]

Just had an amazingly potent shower here with hail and snow and rumbles of thunder.

[Mokidugway]

Just had an amazingly potent shower here with hail and snow and rumbles of thunder.

we caught that earlier , well defined with mammatus !...

[Chris W]

Just had an amazingly potent shower here with hail and snow and rumbles of thunder.

 

We've had some of the rain and hail in Sunderland, but not the thunder and I don't think there was any snow - too near the sea .  Durham is a great place for snow.

[East_England_Stormchaser91]

Quite a few strikes indicated over S Wales, valleys area. Hopefully it stays in tact as it heads ENE.

[Chris W]

Off the UK topic but I thought you guys might like to see this, photographed over Western Australia on my flight from New Zealand to Singapore last week:

 

[Stormyking]

Had yet more thunder and lightning around 4:30am this morning, what a year its been for storms!

[skyblusam]

Just had a heavy hail shower with shotgun thunder and very bright lightning

[Bobby]

A few rumbles of thunder and just now a big flash of fork lightning and big booming thunder. Heard some thunder earlier too.

[rossco89]

Yeah, getting some thunderstorms up here now too.

[Bobby]

More thunder and forked lightning here, nasty hailstorms too. Looks like it has been snowing.

[virtualsphere]

Wife reported thunder & lightning over our house at 5:30am - slept right through it!

[J10]

The amount of hail storms we have had in the past week has been silly.

Wife reported thunder & lightning over our house at 5:30am - slept right through it!

 

Saw one or two flashes past midnight last night.

[Coast]

A couple from GFS that caught my eye:

 

 

[Supacell]

There looks to be a number of convective opportunities over the next few days, especially near to southern and western coasts. 

[Supacell]

An Estofex level 1 along with 50% lightning for some western parts today and into tonight, lightning more likely close to the coast:

 

 

Storm ForecastValid: Tue 31 Dec 2013 06:00 to Wed 01 Jan 2014 06:00 UTCIssued: Mon 30 Dec 2013 22:33Forecaster: TUSCHY

A level 1 was issued for SW Greece and offshore areas mainly for heavy rainfall amounts.A level 1 was issued for parts of Ireland, W Scotland/UK and offshore areas mainly for severe wind gusts. An isolated funnel/short-lived tornado event is possible.SYNOPSIS and DISCUSSIONThe retracted and exceptionally busy pattern over the N-Atlantic continues as another polar vortex approaches E-Canada. In fact, this vortex seems to be the most powerful vortex for this winter season, as 500 hPa heights drop to 481 gpdm and 850 hPa temperatures level out at -37°C! Despite an increasing ensemble spread in numerous oscillation indices, no serious change in the 'roaring 2013/14's' over the N-Atlantic is expected in the near future.Latest OPC analysis places a weakening confluent trough with a filling 990 hPa surface vortex over the N-North Sea. A triple-barrel low with 966 hPa centers covers a broad swath from 45°W to 15°W and 40°N to 70°N. This feature will affect Ireland, UK and Scotland during the forecast with windy and wet conditions and there are a few features to talk about:Extensive N-S aligned cold front already crosses Ireland at 06Z and affects UK/Scotland thereafter (probably leaving UK to the east at roughly 18 Z). Placed in the unfavorable part of that diffluent trough, not much activity is expected convective-wise. Even the most optimistic models show only patches of marginal CAPE along that front and like yesterday we expect some kind of narrow cold-frontal rainband to accompany the wind shift with gusty winds. Constant weakening of that front is forecast.The post-frontal air mass is characterized by rather cold mid-levels with 500 hPa temperature falling to -30 °C or less. Active post-frontal sector with rather deep convection (already visible in latest WV/IR images) spreads east and affects the area of interest between 09 and 00Z. Embedded in this brisk westerly flow regime is a distinct trough axis, which affects Ireland around noon and Scotland thereafter. This time period will probably be the main one for more organized convection. Forecast soundings show 300-400 J/kg SBCAPE and 150-180 m^2/s^2 SRH-1 along that trough. Enhanced LL CAPE exists offshore/along the W-coast of Ireland, so next to enhanced downward mixing of 25 m/s winds at 850 hPa an isolated and short-lived funnel/tornado event seems possible. We would not be surprised to see a rather solid line of enhanced convection to affect W/NW and N-Irland around noon into the early afternoon hours. The level area was also expanded towards W-UK, where onshore moving thunderstorms could see a confined temporal overlap of modest (onshore) SBCAPE and increasing frictional BL shear. A short-lived funnel/tornado event is possible next to the wind risk.During the overnight hours the risk of enhanced and deep convection gradually abates from W to E, as deep WAA sets in from the W ahead of another powerful depression. I don't want to spend too much time on that feature, as the system (or let's say, the most interesting part of that system for convection) remains west of Ireland. Nevertheless there are clear signals of a pronounced tropopause fold and intrusion of high/low tropospheric/stratospheric air, which could overspread the trailing and nearly E-W aligned cold front. Quite robust CAPE signals are forecast and this could result in deep and potentially electrified convection within an environment of 30 m/s near BL winds. Severe wind gusts will be the main hazard, but of interest is a not often seen offshore overlap of roughly 400-800 J/kg SBCAPE and 200 m^2/s^2 SRH-1. Most likely we will never know if a tornado/waterspout occurred with that set-up. Nevertheless, the level 1 was expanded to the SW especially for the enhanced and convectively induced severe wind gust risk.A strong 1030 hPa (plus) high pressure area remains anchored over E-Europe. A small-scale cold-core low still affects Sicily and parts of the Ionian Sea. Slow moving showers/thunderstorms will be the main hazard with sleet, gusty winds and an isolated waterspout risk (although LL CAPE remains meager). The southern part of the warm conveyor belt (WCB) could see some improvement for convection during the overnight hours, which would affect far S-Greece. Some training convection is possible. The slowly eastward spreading WCB brings heavy (stratiform) rain to S-Italy and parts of W/S Greece ... repeatedly onshore moving showers probably cause high rainfall amounts over N-Sicily, too. Only SW Greece and offshore areas were highlighted by a level 1 as confidence in enhanced convection is more elevated compared to the other areas. With that we close the chapter for 2013. We wish everyone a safe and eventful night of New Year's Eve and a Happy New Year.

 

www.estofex.org

Edited December 31, 2013 by Supacell

[Mapantz]

Certainly some surface and mid level CAPE developing as we!l as decreasing ELT's which is good for hail production, it could be a lively new years eve for some.

[Mapantz]

Mixed-layer CAPE outputs indicate the average potential energy of air parcels within the lowest 100mb. They don't represent instability rooted within the mid-levels (i.e. generally between 700 and 500mb). I guess the 'ML' can lead some to assume it's an abbreviation of Mid Level. 

 

Quite right, I was typing fast as I was in the hairdressers waiting for a cutthroat and a haircut and it was close to my turn. LOL